The present invention relates to methods of manufacturing wind turbine blade spar caps and other structural components and to the manufactured components.
A wind turbine blade has a cross-sectional profile of an airfoil such that, during operation, air flows over the blade producing a pressure difference between a pressure side and a suction side of the blade. Consequently, a lift force, which is directed from the pressure side towards the suction side, acts on the blade. The lift force generates torque on a main rotor shaft, which is supplied to a generator for producing electricity.
A wind turbine blade typically includes a suction side and a pressure side. An internal shear web typically extends between the pressure and suction sides and is bonded to spar caps affixed to inner faces of the pressure and suction sides.
The spar cap is often made of composite material and can be manufactured using pre-impregnated composite fibers (otherwise known as pre-preg). The pre-preg material is stored in the form of tapes which are laid down in layers to provide the thickness of the spar cap. The layered material is then cured. However, during the formation of multiple layers from the pre-preg tapes, imperfections such as kinks and wrinkles may become incorporated and later compromise the structural integrity of the spar cap. Additionally, the rate of laydown of pre-preg tapes is often slow, as faster laydown speeds lead to shearing of the previous layer and inclusion of air bubbles, and thus may compromise the structural integrity of the spar cap.
An alternative technique of manufacturing a spar cap is by using laminates from dry unidirectional fabrics. However, perfectly straight fiber alignment is difficult to achieve using this technique, resulting in reduction of compressive strength of the spar cap. Additionally, a slow pace of manufacturing is required for this technique, as faster speeds may lead to shearing of previous layers, which may compromise the structural integrity of the spar cap.
Although spar caps are described herein for purposes of illustration, similar challenges occur in pre-peg manufacturing processes used for other structural components such as subsea risers and gas turbine platforms, for example.
Accordingly, it would be desirable to have an improved method of forming composite spar caps or other such composite structural components.